E3M7: The Chasm (Heretic)

E3M7: The Chasm is the seventh level in The Dome of D'Sparil episode of Heretic. It uses the music track "Marek" by Kevin Schilder.

Essentials
Collect the Ethereal Crossbow in front of you, watching out for ophidians behind the fences on either side, then go up some gray steps to a door which leads to a room with golems. Cross the hall and open the door on the north side, then go round the corner to find one or more fire gargoyles protecting a yellow key door. Go past the door for now and head east round another corner to reach a door leading to a room with undead warriors, then go through the doorway on the south side and go round the corner to find a switch being guarded by a disciple of D'Sparil. Press the switch and kill one or two undead warriors released behind you, then go back to the previous room where you can now climb the stairs by the east wall to reach the yellow key.

Backtrack to the yellow key door and head through it to reach a large orange building surrounded by water, destroy any waiting sabreclaws then head south around the building to find some steps leading up to a hall with more sabreclaws. Go through the west doorway and head straight forward to a switch, watching out for ophidians hiding on either side of it, then press the switch to open the banner wall in the south-east corner and reveal some steps. Go up the steps and kill some waiting gargoyles then press the switch recessed into the south wall; as you do so, note the maulotaur visible through the window. Go back to the hall and approach the horse mural to open it, revealing a room with four teleporters; kill or dodge the maulotaur and enter the north-east teleporter to reach a room overlooking the hall, press the switch in the north wall then drop down to the hall and return to the teleporters. The south-east teleporter has lowered, allowing you to reach the green key.

Go back to the hall and open the east door, head down a staircase then follow the passage west to a cavern with sabreclaws. Head south to a water pool and exit through the doorway in the south-west corner, then follow the path past a weredragon and go up to a bridge over a sludge pit. Cross the bridge, watching out for iron liches on either side as well as a strong wind that tries to push you off, and collect the blue key on the other side along with a Wings of Wrath, then retrace your steps to the orange building at the north end of the level. Go up the steps on the south side of the building and open a stone door at the top, destroy any waiting liches then open the exit door and press a switch behind it to finish the level.

Secrets

 * 1) Open the horse mural opposite the yellow key door to find one to three weredragons guarding a Tome of Power and a Claw Orb. (sector 21) Pressing the switch here will lower a teleporter on your left, which leads to a chamber with an Energy Orb guarded by a sabreclaw. There is another switch behind you that will lower a second teleporter, leading to another chamber with a sabreclaw protecting a Dragon Claw. Press a third switch behind you to lower another teleporter which leads back to the secret area.
 * 2) In the room with four teleporters, enter the north-west teleporter then press the switch on the north wall. When you return to the teleporter room you will see that the south-west teleporter has lowered; this teleporter is fake (it has no teleport glitter), but stepping on it will open the south wall and reveal one to three disciples guarding a Hellstaff. (sector 147)
 * 3) From the chamber with the green key, open the misaligned south wall to find one or two weredragons guarding a number of Timebombs of the Ancients. (sector 160)
 * 4) Just before reaching the bridge to the blue key, you must walk through a water pool containing a weredragon. Open the west wall before this pool, next to a Flame Orb, to find a Phoenix Rod. (sector 173)
 * 5) Next to the blue key is a Wings of Wrath. As soon as you pick it up, activate it then fly west over the sludge pit to a ledge with various ammo pickups. (sector 192) The ledge leads to an enclosed area with a Ring of Invulnerability, another Wings of Wrath and one of each large ammo pickup.
 * 6) From secret #5, fly east over the sludge until you reach another ledge in the south-east corner with more ammo pickups. (sector 205) The ledge leads to another enclosed area with an Enchanted Shield, another Wings of Wrath and one of each large ammo pickup.
 * 7) Entering the cavern with the blue key opens four closets in the large cavern you passed through after passing the green key door, all of which count as separate secrets. The first closet is in the south-east corner of the water pool and holds a Mystic Urn. (sector 203)
 * 8) The second closet is in the north-west corner of the water pool and holds a Map Scroll. (sector 178)
 * 9) The third closet is east of the water pool, in a brightly-lit sector with Gauntlets of the Necromancer, and holds a Tome of Power. (sector 200)
 * 10) The final closet is south of the passage leading into this cavern, and holds a Chaos Device. (sector 162)

Bugs

 * Linedefs 84, 89, 143 and 154-160, found in the underground cavern before the sludge pit, have their upper textures set on the wrong side. All the wall sections are 16 map units high, and the ceiling flats of the adjacent sectors leak over them.

Current records
The records for the map at the Doom Speed Demo Archive are:

The data was last verified in its entirety on May 12, 2023.

Player spawns
This level contains four spawn points:
 * 1) facing east. (thing 4)
 * 2) facing south. (thing 644)
 * 3) facing east. (thing 645)
 * 4) facing west. (thing 646)

Things
This level contains the following numbers of things per skill level: